RESEARCH ARTICLE Microcontroller-based simple maximum power point tracking controller for single-stage solar stand-alone water pumping system P. Packiam*, N. K.Jain and I. P. Singh Instrument Design Development Centre, Indian Institute of Technology Delhi, New Delhi, India ABSTRACT A simple microcontroller-based maximum power point tracking controller is proposed for a single-stage solar stand-alone water pumping system for remote, isolated, and nonelectrified population, where less maintenance, low cost, and an effi- cient system is of prime interest. It consists of a photovoltaic (PV) module, a DC–AC converter utilizing space-vector pulse-width modulation, an induction motor coupled with a water pump, a voltage sensor, and a current sensor. A space-vector pulse-width modulation-controlled DC–AC converter aided by a fast-acting on–off supervisory controller with a modified perturb-and-observe algorithm performs both the functions of converting PV output voltage to a variable voltage, variable frequency output, as well as extracting the maximum power. A limited variable step size is preferred dur- ing transient state, and a steady frequency, which is calculated on the basis of steady-state oscillation, is set during steady state. A fast-acting on–off supervisory controller regulates DC link voltage during steady state and enables maximum power point tracking algorithm only during transient state to draw a new voltage reference. In the event of low voltage, the controller switches off the motor but continuously scans for an available PV voltage. The system is not protected against an overcurrent because the maximum current is equal to its short circuit current. The 16-bit microcontroller dsPIC6010A (Microchip Technology, Inc., Chandler, AZ, USA) is used to implement the control functions. The proposed controller is verified through simulation as well as tested in the laboratory prototype model. The simulation and experimental results show good correlation. Copyright © 2011 John Wiley & Sons, Ltd. KEYWORDS DC–AC inverter; induction motor; microcontroller implementation; MPPT controller; PV water pumping system; single stage; steady and transient performance; SVPWM *Correspondence P. Packiam, Instrument Design Development Centre, Indian Institute of Technology Delhi, New Delhi 110016, India. E-mail: packiamp@gmail.com Received 5 May 2011; Revised 13 July 2011; Accepted 26 August 2011 1. INTRODUCTION Solar energy sources for water pumping applications are becom- ing increasingly important for remote, isolated, and nonelectri- fied population, where access to grid is impractical or costly to implement. Even grid-fed pumps used for edible and irrigation purposes need to be reviewed for the following reasons: cost of motor burnouts, expenses incurred for repairing machinery because of voltage fluctuations, lower crop yields because of irrigation activities affected by short fall in the supply of electric- ity, requirement of government subsidies, and transmission and distribution losses. The main drawback of photovoltaic (PV)- operated system is that the initial installation cost is considerably high. But advancement in the design of motors, availability of cost-efficient high-speed digital signal controllers, drastic decrease in the cost of PV modules, and rapid developments in state-of-the art power conversion devices are to be counter- weighed in addition to the advantages of solar energy; it is abun- dant, clean, modular in nature, with no running cost, and a short gestation period. In general, permanent magnet brushless DC motors fed by solar power are being used for water pumping [1]. But difficulties in the availability of permanent magnet motors, frequent maintenance, and high cost are still major hurdles in their application. In such circumstances, the variable fre- quency drives using induction motor (IM) [2,3,7,8] offer a better choice in terms of availability, cost, maintenance, rugged design, and size in comparison with DC motors. PROGRESS IN PHOTOVOLTAICS: RESEARCH AND APPLICATIONS Prog. Photovolt: Res. Appl. (2011) Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/pip.1207 Copyright © 2011 John Wiley & Sons, Ltd.